Manufacture of abrasive materials



1947- s. w. DRONSFIELD 2,426,441

' MANUFACTURE OF ABRASIVE MATER IALS Filed Dec. 7, 1944 INVENTOR.bYZuavI /EZ I store it under conditions Patented Aug. 26, 1947MANUFACTURE OF ABBASIVE MATERIALS Samuel Wilkinson Dronsfield, Wilmslow,England Application December 7, 1944, Serial No.

In Great Britain January 1, 194 4 1 Claim. (01. 51-185) This inventionrelates to improvements in the- -manufacture of emery fillet, especiallygrooved emery fillet.

Emery'fillet, consisting of narrow fabric coated on one side with anabrasive such as emery, garnet or corundum, is employed ,for winding oncylinders or rollers to serve for the grinding of card clothing oncylinders and dofiers, carding machines or the like.

Card clothing which is'used on cylinders, doffers, carding machines andthe like in the textile industry is customarily subjected to what istermed "grinding after manufacture and at intervals during its use. Insuch grinding the tips of the wires are brought into light contact withan abrasive material, such as emery, secured to the face of a roller orcylinder which is rotated and may be traversed over the work.

One method of making such a card grinding cylinder or roller consists inwinding the material known as emery fillet around the roller andsecuring it in position so as to provide a substantially unbroken areaof abrasive material on the surface of the roller.

One method of'manufacturing emery fillet is to take a narrow wovenfabric. of cotton, linen, or cotton and linen, apply to one face apreparation of animal glue and cause emery powder to be adhered to theglue and then allow it to dry. This gives a fillet having a thin coatingof abrasive which can be wound on cylinders and rollers and gives usefulresults in many cases. It is better, however, before allowing thecoating to dry, to provide the material with longitudinal grooves, forexample by passing it into contact with the face of a'grooved roller.Such longitudinal grooving is known to be valuable in emery fillet butits best eflect is exhibited on double coated fillet. In the case ofsuch double coated fillet, a further layer of animal glue is applied tothe first layer before'grooving and a further coating of emery powdercaused to adhere thereto whereafter the double coating is grooved andallowed to dry.

Although preparations of animal glue are satisfactory as adhesives whenthe material is in use, there is a risk of double coated grooved emeryfillet becoming too hard or too soft during storage owing to changes inatmospheric conditions. Frequently it is necessary to store suchemery-fillet under conditions of high temperature and humidity, as forexample in India, or 'to of low temperature and/or'low humidity. If themaerial becomes unduly softened it may be spoiled and if it be- 2 comesunduly hard it may crack or break when an attempt is made to wind it onthe card grinding rollers or cylinders.

I have found that these difliculties can be overcome by employing as theadhesive for the abrasive powder, a plastic or plasticised syntheticresin. I have further found that plasticised ureaformaldehyde resins,especially combinations .of urea-formaldehyde resins, and alkyd resinsare particularly useful for this purpose.

Certain precautionshave to be observed, how'- ever, when usingplasticised synthetic resins as adhesives for the abrasive powder inmaking grooved emery fillet, especially double coated,

grooved emery fillet.

1. The synthetic resin composition chosen must be such that it does notundergo any undesirable alteration in hardness or adhesive propertiesunder any atmospheric conditions likely to be encountered duringstorage. Synthetic resins are in general unaffected by moisture and inorder to avoid embrittlement at low temperatures it is necessary eitherto employ a thermoplastic resin which has a high degree of flexibilityat low temperatures or to employ a plasticised resin which may be of thethermoplastic or thermosetting type. I

2. It is important to avoid stiffening of the fabric. This involves theuse of a resin composition which, if it penetrates the fabric, is highlyflexible. I

3. Whether the synthetic resin composition penetrates the composition ornot, it must be sufflciently flexible to enable the coating to bendwithout detachment from the support and without breaking away of theadhesive when the fillet is wound on a cylinder or roller and to enableit to stand the grooving operation. 4

In the practice of the present invention it is preferred to employ aplasticised thermo-hardening resin since thermo-hardening resins tend tosuffer less change in plasticity under changes of atmosphericaltemperature. It is preferred, however, to use a preparation which can becured at a fairly low temperature, i. e. below 212 F. and preferably ator only a little above atmospheric temperature. When usingthermo-hardening resin it is essential to avoid the use of such longtimes and/or high temperatures of heating that brittleness develops. Ifthis occurs, the emery fillet may. crack when wound on the cylindersand/or the abrasive may easily rub off. The time,

and temperature of heating must be such that the synthetic. resin is nolonger sticky but is quite firm, flexible and water-resistant. 1

As already stated, I have found urea-formaldehyde resins suitable foruse in practicing the present invention especially when piasticised withallwd resins. The invention, however, is not limited to these sinceother resins may be used, for example, melamine formaldehyde products. Iuse the expression synthetic" resin, however, in a broad sense asincluding artificialcondensation products such as phenol formaldehydeproducts, urea and thiourea formaldehyde products,po1ybasic-acid-polyhydric-alcohol condensation products, amineformaldehyde condensation products and the like, polymerisation productssuch as polyvinyl halides, polyvinyl esters, polystyrene derivatives,polymerised acrylic acid esters, and the like, as well as plasticmaterials of the type of cellulose esters such as cellulose acetate andcellulose nitrate. It has been found, however, that most of thethermoplastic material, especially cellulose acetate and polyvinylesters, do not readily wet the particles of emery and satisfactory adhesion of the emery can be secured only by mixing it with thethermoplastic material before coating. This involves difilculties inspreading the material on the narrow fabric base, which are particularlynoticeable with the extremely coarse abrasives I used in emery fillet,and accordingly mixing of the abrasive with the adhesive before coatingis less preferable.

One suitable composition which can be used consists of a mixture ofurea-formaldehyde resin such as that sold under the trade name of ResinU. G., and of alkyd resin such as that sold under the trade name ofResin R. P. 8 in the proportion of one part of the former to two of thelatter. By the incorporation of a known acidic hardening agent into thismixture hardening can be effected at temperatures below 212 F. and evenbelow 100 F., e. g. at room temperatures. The alkyd resin serves as aplasticiser for the ureaformaldehyde resin and gives a bonding agentwhich is sufllciently flexible to furnish an emery fillet of the samedegree offlexlbility as that obtained with the customary animal gluepreparations.

Other suitable resin compositions are (a) that sold by British ResinProducts under the trade name Epok, which is an oil-modified phenolicresin dissolved in xylol (70% resin), (b) a mixture of equal proportionsof the resins sold by I. C. I. under the trade names "Paralac 100," and"Paralac 2851!." These are Glyptal resins. (c) That sold by BritishResin Products under the trade name Distrene. This is a polystyreneresin.

The general procedure in making emery fillet material is applied overthe emery treated covering before grooving and a further quantity ofemery particles applied.

In the accompanying drawings:

Fig. 1 shows an elevation of a roll of emery fillet made in accordancewith this invention,

Fig. 2 shows on a larger scale a plan view of the coated side of a partof the emery fillet shown in Fig. 1,

Fig. 3 is a side sectional elevation on a. still larger scale of theemery fillet shown in Fig, 1.

As shown in the drawings, the narrow textile fabric support i carries aflexible coating 2 composed of an alkyd resin piasticisedureaformaldehyde resin adhered to which are coarse emery particles 3.

As efio wn in Fig. 3, the coating 2 is formed of ms separately appliedlayers In. and 2b identical in composition. They are shown, forconvenience,

as separated by a line but they form together a unitary coating which islongitudinally grooved as shown at inFig. 2.

Examples of resinous compositions which may be used will now be given.

Example 1 An etherified urea-formaldehyde resin plasticised with analkyd resin dissolved in butyl alcohoi.

The urea-formaldehyde resin is one made by condensing one molecularproportion of urea with three molecular proportions of formaldehyde inthe presence of butyl alcohol, the mixture being on the alkaline side ofneutrality and heated under reflux at 100 C. for one hour. At the end ofthis time the mixture is acidified and the water boiled oil. as anazeotropic mixture with butyl alcohol, leaving the etherified resin inbutyl alcohol solution.

The alkyd resin is made by heating a. mixture of 148 parts by weight ofphthalic anhydride, 47 parts by weight of glycerol, 15 parts by weightof glycol and 152 parts by weight of castor oil, under reflux allowingescape of water in an inert atmosphere at 420 F. for 6 to 8 hours untila suitable acid value and viscosity are obtained.

'1 parts by weight of each of the above resins is dissolved in 5 partsby weight of xylene and 1 according to the present invention is asfollows:

The narrow fabric is wound spirally on to a cylinder so as to cover thesurface thereof. It is then painted by brushing or spraying with asolution of resinous material in a solvent. Then a coating of emeryparticles of any suitable fineness is dusted on. While the coating isstill plastic the cylinder is revolved in contact with a ribbed rollerhaving, for example, twelve ribs to the inch, each rib aboutone-sixteenth of an inch deep. This produces grooves in the coatingalong the length of the fabric. The coating is then allowed to dry withheating if necessary (e. g. to about 100 F.) preferably with warm air,in order to dry oil the solvent and harden the resin it this is of thethermo-hardening or polymerisable type. Finally, the emery fillet isunwound from the cylinder and made up into rolls. I

If desired, a further coating of the resinous part by weight of an acidorganic ester of phcs-- phoric acid is added to accelerate thehardening.

Example 2 An ammonia catalysed cresol-iforrnaldehyde resin made bycondensing 1 molecular proportion of 60% metacresol with 1.4 molecularproportions of formaldehyde using 0.05% by weight of 0.880 ammonia(calculated on the cresol) as catalyst.

Example 3 Parts by weight Phthalic anhydride 15o Glycerol Castor iExample 4. Polystyrene Purified monomeric styrene is polymerised aloneor in aqueous emulsion by heating at 100- 160 C. in the presence of 0.1to 1% of an oxidation catalyst such as benzoyl peroxide. Themolecularweight of the product obtained is higher or lower according towhether the concentration of catalyst and/or the temperature is higheror lower.

I declare that what I claim is:

The method of making a flexible, substantially longitudinally groovedemery fillet capable of being wound around a cylindrical roller toprovide a substantially unbroken circumferentially grooved area ofabrasive material on the surface thereof which will serve for thegrinding of card clothing, which consists in wrapping a narrow textilefabric around a. cylinder to cover the surface thereof, applying to theexposed face of said fabric a first solution in volatile solvent of analkyd resin plasticised urea formaldehyde resin capable of'being curedat a temperature below 212 F.,

dusting coarse emery particles on the coating formed by said firstsolution, applying to said coating 9. second solution in volatilesolvent of an alkyd resin plasticlsed urea formaldehyde resin capable ofbeing cured at a temperature below 212 F. dusting further coarse emeryparticles on the combined coating of saidflrst and second solutions,revolving the cylinder carrying said cure the resin and finally removingthe coate fabric'with the coated surface of said contact with a ribbedroller to produce complementary grooving in the combined coating on'said fabric, bringing the coated fabric into contact with warm air toremove all solvent and fabric from said cylinder.

SAMUEL WILKINSON DRONSFIELD.

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